Notifying the general public in a selected area of an approaching emergency event has always been an important issue.
The area of telecommunication offers the possibility to reach a subscriber associated with a terminal via a message. 3rd Generation Partnership Project (3GPP) specifies a “Broadcast”-procedure usable for notifying terminals about an emergency event. Broadcasting makes use of sending a message to terminals in a particular network area via a selected channel. The Broadcast procedure is specified as a Cell Broadcast System (CBS), for example, in 3GPP Technical Specification (TS) 23.041, and is usable in the context of Public Warning Systems (PWS), as specified in 3GPP TS22.268. However, the extension of the target network area to be reached via the broadcast procedure may be selected at call level extension. Further, a message length may be limited owing to the used broadcast channel throughput.
Further, it is known to send a Short Message Service (SMS) to a selected terminal, in order to notify the terminal of an approaching event. In general, sending a SMS is a terminal specific procedure but not dedicated to a selected target network area. Further, the actual location of the terminal has to be permanently tracked for the sending of the SMS.
In order to keep track of the actual location of the terminal, location update signaling sent from a Mobile Switching Center (MSC)/Visitor Location Register (VLR) of a home network to a respective Home Location Register (HLR) may be intercepted, and information about subscribers having roamed into the serving network area of the responsible MSC may be accordingly stored. However, the latter may not allow for actually localizing the terminal within an extension of a serving network area of the MSC, and may thus limit the extension of the target network area to the extension of the serving network area. This problem may even be multiplied in a case in which the MSC may form part of a pool of MSCs.
Further, in order to locate the selected terminal, it may be possible to intercept the signaling at the A-/Iu-interface between a Base Station Subsystem (BSS) and the MSC such that all mobility management procedures executed by all terminals in the serving network area of the MSC are tracked. However, the information about the actual location of all terminals may have to be stored in an external database for a later evaluating. Further, such a monitoring of a movement of a terminal and thus its associated subscriber may be subject to a governmental authorization, which may be legally prohibited in a large number of countries, as it is the case in Germany.
It is also known to use a Customized Applications for Mobile networks Enhanced Logic (CAMEL) “MM Notify” procedure executed by the VLR when a respective MSC receives location update signaling traffic from the selected terminal, and to store the information about the actual location of the terminals. However, this continuous tracking of a location of terminals in the serving network area may require additional effort. Further, the terminals to be tracked may have to be subscribed to this procedure, which may add a lot of signaling traffic even if no SMS may have to be sent to the terminals.
Accordingly, the above described techniques for notifying terminals in a target network area may require additional effort, hardware or signaling traffic within the network, but may comprise a low geographical precision concerning the actual location of the terminal, and may cause legal problems.